JPH10232315A - Holographic optical member - Google Patents

Abstract

PROBLEM TO BE SOLVED: To eliminate the influence of adhesives on the diffraction characteristics of a hologram by interposing a color tuning layer which widens or shifts the region of the diffraction wavelengths of a volume phase type hologram layer between a volume phase type hologram layer and an adherend at the time of adhering the latter to the former. SOLUTION: The back light side polarizing plate 47 of a liquid crystal display element 40 is adhered and integrated with a diffusion reflection type hologram by applying the adhesive 3 on the color tuning film 2 side of the diffusion reflection type hologram, by which a liquid crystal display device allowing a bright display without using a back light of spontaneous light emission type in a bright place is constituted. In such a case, the plasticizer, etc., in the adhesive 3 are used for color tuning and are blocked by the remaining color tuning film 2 and, therefore, the plasticizer, etc., hardly arrive at the hologram layer 1 and consequently, the diffraction characteristics of the hologram are not affected at all. As a result, the hologram layer 1 is capable of maintaining the as- designed stable diffraction characteristics.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a holographic optical member, and more particularly, to a holographic optical member in which an adhesive or the like does not affect a diffraction characteristic when a volume hologram is bonded.

[0002]

2. Description of the Related Art The present applicant has proposed a liquid crystal display device using a diffuse reflection type hologram in Japanese Patent Application No. 7-313362. That is, a diffuse reflection hologram that diffuses and reflects light incident from a specific direction only in a direction defined as an observation area is a Lippmann hologram using a scattering plate as a subject, and a paper titled "Holographic and Interferometr".
ic Viewing Screens "(by Dietrich Meyerhofer, APPLIED
OPTICS / Vol. 12, No. 9 / September 1973), and U.S. Pat. No. 5,046,793. There are several methods for producing a diffuse reflection hologram composed of a Lippmann hologram (volume hologram).
11 shows a one-step imaging method, and FIG. 11 shows a two-step imaging method. In the one-step imaging method shown in FIG. 10, a reflection type hologram dry plate (Lipman hologram dry plate) 11 such as a photopolymer is arranged at a position previously defined as a diffuse reflection region with respect to a scattering plate 10 such as a ground glass, Coherent light 1 of a predetermined wavelength divided into two from the same light source from the back of
The scattered light 14 illuminated by the light source 2 and emitted to the front surface of the scattering plate 10 is incident on the reflection hologram dry plate 11 as object light, and another coherent light 13 of a predetermined wavelength divided into two from the same light source is used as reference light. Then, the diffuse reflection hologram is recorded on the reflection hologram dry plate 11 by making the reference light 13 proceeding in the opposite direction to the incident light assumed by the diffuse reflection hologram from the side opposite to the scattered light 14.

In the two-step photographing method shown in FIG. 11, as shown in FIG. 11A, a transmission type hologram dry plate 15 is arranged at a position predetermined as a diffuse reflection region with respect to a scattering plate 10 such as ground glass. At the same time, the light is illuminated from the back of the scattering plate 10 with the coherent light 12 having a predetermined wavelength divided by two from the same light source, and the scattered light 14 emitted to the front of the scattering plate 10 is incident on the transmission type hologram dry plate 15 as object light. By making another coherent light 16 of a predetermined wavelength divided by the same light source into a reference light and incident at an arbitrary angle from the same surface side as the scattered light 14, the first light is incident on the transmission type hologram dry plate 15.
The transmission hologram, which is the hologram of the above, is recorded.

Next, the first hologram is designated as 17,
As shown in FIG. 11B, the hologram 17 is disposed at the position of the original transmission hologram dry plate 15 and the reflection hologram dry plate 20 is disposed at the position of the scattering plate 10.
The hologram 17 is reproduced at the same wavelength that travels to the opposite side of the reference light 16 at the time of recording so that the real image of the hologram 17 is formed at the position of the reflection type hologram dry plate 20 (the position of the scattering plate 10 in FIG. 9A). The hologram 17 is irradiated with illumination light 18.
Diffracted light 19 from the hologram is incident on the reflection hologram dry plate 20 as object light, and the reference light 21 traveling in the opposite direction to the incident light assumed in the diffuse reflection hologram is incident from the opposite side of the reflection hologram dry plate 20. Thus, a diffuse reflection hologram as a second hologram is recorded on the reflection hologram dry plate 20. With this method, a diffuse reflection hologram that limits the observation area to the range of the first hologram 17 can be manufactured. Further, using this hologram as an original, the hologram that is closely copied is also a diffuse reflection hologram in which the diffraction direction (scattering direction) of the original is maintained.

[0005] The diffuse reflection hologram 31 obtained as described above is connected to a liquid crystal display element 40 as shown in cross section in FIG.
Of the liquid crystal display device 40, the illuminating light 32 incident from the display side of the liquid crystal display element 40 is diffused only in the angle range θ that matches the observation area of the liquid crystal display device.
As 3, the liquid crystal display device capable of diffuse reflection and capable of bright display in a light place without using a self-luminous backlight can be configured. Here, the liquid crystal display element 40 is composed of, for example, a liquid crystal layer 45 such as twisted nematic sandwiched between two glass substrates 41 and 42, and a uniform transparent counter electrode is formed on the inner surface of one of the glass substrates 42. A transparent display electrode 43 and a black matrix (not shown) are provided independently for each pixel on the inner surface of the other glass substrate 41. In the case of a color display device, the liquid crystal cell R,
A transparent display electrode 43, a color filter, and a black matrix are provided independently for each of G and B. Also,
An alignment layer (not shown) is also provided on the liquid crystal layer 45 side of the electrodes 43 and 44. Further, a polarizing plate 46 is provided on the outer surface of the observation-side glass substrate 41, and an outer surface of the glass substrate 42 on the opposite side to the observation side. , Polarizing plates 47 are adhered, for example, and their transmission axes are arranged to be orthogonal to each other. Display is possible by controlling the voltage applied between the transparent display electrodes for each pixel of the liquid crystal display element 40 and changing the transmission state. In the arrangement of FIG. 8, by providing a diffuse reflection plate or a reflection plate on the back side of the diffuse reflection hologram 31, it is possible to further improve the brightness.

Further, by utilizing the characteristic of diffracting only a specific wavelength of a reflection type hologram and transmitting light in other wavelength ranges, FIG.
As shown in the figure, by using a self-luminous backlight 34 on the back side of the diffuse reflection type hologram 31, illumination is performed by light 35 from the self-luminous backlight 34 in a dark place, and a self-luminous type backlight is used in a bright place. By reducing or extinguishing the brightness of the backlight 31, and illuminating with the diffuse reflection light 33 of the external light 32, the battery driving time of a device using a liquid crystal display device such as a portable computer can be greatly extended. .

As described above, a photopolymer has recently been used as a recording material for a diffuse reflection hologram. The diffraction wavelength characteristic of a volume phase hologram recorded in a photopolymer by two-beam interference is narrow. Therefore, this diffraction wavelength characteristic is expanded, and
It is known to use a color tuning technique on a hologram after interference recording in order to adjust the diffraction wavelength (JP-A-3-46687). This color tuning is a technology that broadens the diffraction wavelength by diffusing monomers, plasticizers, etc. into the photosensitive material by heating the color tuning film by bringing the color tuning film into close contact with a photosensitive material such as a photopolymer on which a hologram is recorded. In addition, since the half-width of the diffraction wavelength increases, when the Lippman hologram after color tuning is illuminated with white light, the amount of diffracted light increases and the luminance improves. At the same time, such color tuning involves a phenomenon that the center diffraction wavelength shifts to a longer wavelength side. The color tuning film is
In general, the matrix polymer contains a monomer having high mobility and a polymerization initiator.

[0008] A method of obtaining a color pattern having different reproduction colors according to positions from a volume hologram in which uniform interference fringes are recorded using a color tuning film is also disclosed.
It is proposed by the present applicant in Japanese Patent Application No. 5-120016.

[0009]

By the way, a volume hologram having a refractive index distribution inside a material such as the above-mentioned diffuse reflection type hologram or color patterned volume hologram is adhered to avoid the influence of interface reflection. When bonding to an adherend such as the liquid crystal display element 40 of FIG. 8 using an agent or the like, a protective PET layer usually laminated on a photopolymer is used.
When a (polyethylene terephthalate) film is interposed, the PET film has optical anisotropy, which adversely affects the polarization characteristics, and is particularly problematic when the film is adhered to a liquid crystal display device. Therefore, it is conceivable that the hologram layer is exposed, and an adhesive or an adhesive is applied thereon and adhered. However, a plasticizer or the like in the adhesive or the adhesive has an effect on the hologram layer, and the hologram layer will be described later. As exemplified in the example, problems such as a change in the diffraction characteristic of the hologram and a shift in the diffraction wavelength occur.

The present invention has been made in view of such a situation, and an object of the present invention is to provide a holographic optical member which eliminates the influence of a pressure-sensitive adhesive or the like on diffraction characteristics when a volume hologram is bonded. It is to be.

[0011]

A holographic optical member according to the present invention for achieving the above object has a hologram layer of a volume phase type, and the diffraction wavelength of the hologram layer is broadened adjacent to the hologram layer. A holographic optical member obtained by laminating a laminate having a shifted color tuning layer to an adherend with an adhesive layer, wherein the adhesive layer is located on the color tuning layer side. Is what you do.

In this case, the hologram layer is made of a photopolymer or the like. The color tuning layer is typically a matrix polymer containing a monomer having high mobility and a polymerization initiator.

The hologram layer is a diffuse reflection type hologram or a color tunable layer in which uniform interference fringes recorded inside the hologram layer are tuned by the color tuning layer so that reproduced colors are different depending on positions. Preferably, there is.

In the present invention, when the volume phase type hologram layer is adhered to the adherend, a color tuning layer in which the diffraction wavelength of the hologram layer is widened or shifted is interposed therebetween. Since the plasticizer or the like is blocked by the color tuning layer and does not reach the hologram layer, the influence of the adhesive on the diffraction characteristics of the hologram can be eliminated.

[0015]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The principle and embodiments of the holographic optical member of the present invention will be described below. FIG. 1 shows, as an example, a volume hologram on the backlight side of the liquid crystal display element 40 as shown in FIG.
FIG. 3 is a cross-sectional view of a configuration in which a diffuse reflection hologram manufactured by the method as described above is attached to a diffuse reflection hologram whose diffraction wavelength characteristics are broadened and the diffraction wavelength is adjusted by a color tuning technique. In the present invention, the hologram layer 1 of the diffuse reflection type hologram is made of a Lippmann hologram dry plate such as a photopolymer, and FIG.
The wavefront from the scattering plate 10 is interference-recorded by a method such as
Thereafter, the color tuning film 2 is adhered to one surface and subjected to a heat treatment, so that the reproduction wavelength is shifted from the wavelength at the time of recording to the longer wavelength side and the diffraction wavelength is broadened. After the processing, the color tuning film 2 is integrated without being separated from the hologram layer 1, and the PET film 4 is laminated on the other surface of the hologram layer 1.

The adhesive 3 is applied to the color tuning film 2 side of the diffuse reflection type hologram having such a configuration, and is adhered and integrated on the backlight-side polarizing plate 47 of the liquid crystal display element 40, so that it can be used in a light place. 2. Description of the Related Art A liquid crystal display device capable of performing bright display without using a self-luminous type backlight is configured.

With such a configuration, the plasticizer and the like in the adhesive 3 are blocked by the remaining color tuning film 2 used for color tuning.
It hardly reaches the hologram layer 1 and therefore has no effect on the diffraction characteristics of the hologram. Therefore, the hologram layer 1 can maintain a stable diffraction characteristic as designed.

Hereinafter, a specific example will be described. FIG. 2 is a diagram showing the diffusion characteristics of a diffuse reflection hologram master. On this diffuse reflection type hologram master, Omnidex 706M manufactured by DuPont as a Lippmann hologram photosensitive material made of a photopolymer is superimposed, and a laser beam having a wavelength of 488 nm is incident from the photosensitive material side at an incident angle of 15 ° with respect to a normal line, and diffusely reflected. The hologram master was duplicated. The diffraction spectral characteristics at room temperature of the duplicated diffuse reflection hologram were as shown in FIG. However, the diagram showing the diffraction spectral characteristics is shown as a change in the spectral transmittance (zero-order light), and the lower the transmittance, the higher the diffraction ratio.
same as below.

The duplicate diffuse reflection hologram is used as a color tuning film as CTF7 manufactured by DuPont.
5 were baked at 140 ° C. for 6 minutes, and then fixed by irradiation with ultraviolet rays. In addition, the color tuning film was left as one. Four such samples were produced.

The change in the diffraction spectral characteristics of the first sample as a reference for 20 days was measured, and the result was as shown in FIG.

With respect to the second sample, PN-15 with a PET film manufactured by Lintec as an adhesive was laminated on the color tuning film that had been left as a single piece, and the change in diffraction spectral characteristics for 20 days was measured in the same manner. FIG.

For the third sample, the same adhesive was directly laminated on the diffuse reflection type hologram layer on the side opposite to the color tuning film, bonded and integrated with the PET film, and similarly, the diffraction spectral characteristics for 20 days were obtained. When the change was measured, it was as shown in FIG.

With respect to the fourth sample, the same adhesive was laminated on both sides of the color tuning film that had been left integrally and on the diffuse reflection type hologram layer opposite to the color tuning film, and the PET film was laminated from both sides. Was adhered, and the change in diffraction spectral characteristics for 20 days was measured in the same manner. The result was as shown in FIG.

The amount of shift of the diffraction wavelength peak toward the blue side of the reference of the first sample for 20 days is 3.2 nm,
The shift amount of the similar diffraction wavelength peak of the second sample is 4.4 nm, the shift amount of the similar diffraction wavelength peak of the third sample is 8.6 nm, and the shift amount of the similar diffraction wavelength peak of the fourth sample is When the wavelength shift of the reference of the first sample is offset, the wavelength shift is 1.2 nm for the second sample, 5.4 nm for the third sample, and 6.9 nm for the fourth sample. Thus, it was confirmed that when a color-tuned volume phase hologram was attached to the adherend, the effect of the adhesive on the hologram diffraction characteristics could be almost eliminated by adhering through the color tuning film.

The holographic optical member of the present invention has been described above with reference to a liquid crystal display element to which a diffuse reflection type hologram is attached, but in addition to the above, a volume obtained by forming a color pattern using a color tuning film. The same applies to the case where a hologram or the like is attached to another adherend such as a transparent substrate.

[0026]

As is apparent from the above description, according to the holographic optical member of the present invention, when the volume phase type hologram layer is bonded to the adherend, the diffraction wavelength of the hologram layer is broadened or shifted. Since the color tuning layer is interposed between the hologram layer and the plasticizer in the adhesive is blocked by the color tuning layer and does not reach the hologram layer, the influence of the adhesive on the diffraction characteristics of the hologram can be eliminated. .

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a configuration in which a diffuse reflection hologram is attached to a liquid crystal display element according to the present invention.

FIG. 2 is a diagram showing diffusion characteristics of a diffuse reflection hologram master in one specific example.

FIG. 3 is a diagram showing diffraction spectral characteristics of a diffuse reflection hologram copied from an original.

FIG. 4 is a diagram showing a change in diffraction spectral characteristics of a reference.

FIG. 5 is a diagram showing a change in diffraction spectral characteristics of a sample obtained by applying an adhesive on a color tuning film.

FIG. 6 is a diagram showing a change in diffraction spectral characteristics of a sample in which an adhesive is applied on a hologram layer.

FIG. 7 is a diagram showing a change in diffraction spectral characteristics of a sample in which an adhesive is applied on a color tuning film and a hologram layer.

FIG. 8 is a sectional view of a liquid crystal display device provided with a diffuse reflection hologram.

FIG. 9 is a cross-sectional view of another liquid crystal display device provided with a diffuse reflection type hologram.

FIG. 10 is a diagram for explaining a method of manufacturing a diffuse reflection hologram by a one-step imaging method.

FIG. 11 is a diagram for explaining a method for producing a diffuse reflection hologram by a two-step photographing method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Hologram layer 2 ... Color tuning film 3 ... Adhesive 4 ... PET film 32 ... Illumination light 33 ... Diffusion light 40 ... Liquid crystal display element 41, 42 ... Glass substrate 43 ... Transparent display electrode 44 ... Transparent counter electrode 45 ... Liquid crystal layer 46, 47: Polarizing plate

Claims (5)

[Claims] 1. A laminate having a volume phase type hologram layer and a color tuning layer adjacent to the hologram layer and having a broadened or shifted diffraction wavelength of the hologram layer is bonded by an adhesive layer. A holographic optical member bonded to a body, wherein the adhesive layer is located on the color tuning layer side. 2. The holographic optical member according to claim 1, wherein said hologram layer is made of a photopolymer. 3. The holographic optical member according to claim 1, wherein the color tuning layer comprises a matrix polymer containing a monomer having a high mobility and a polymerization initiator. 4. The holographic optical member according to claim 1, wherein a diffuse reflection hologram is recorded on the hologram layer. 5. The hologram layer is characterized in that uniform interference fringes recorded in the hologram layer are color-tuned by the color tuning layer so that reproduced colors are different according to positions. The holographic optical member according to claim 1.